Phenotype

In genetics, the phenotype (from Ancient Greek φαίνω (phaínō) 'to appear, show' and τύπος (túpos) 'mark, type') is the set of observable characteristics or traits of an organism.

[4][5] The distinction resembles that proposed by August Weismann (1834–1914), who distinguished between germ plasm (heredity) and somatic cells (the body).

Most molecules and structures coded by the genetic material are not visible in the appearance of an organism, yet they are observable (for example by Western blotting) and are thus part of the phenotype; human blood groups are an example.

The term was first used by Davis in 1949, "We here propose the name phenome for the sum total of extragenic, non-autoreproductive portions of the cell, whether cytoplasmic or nuclear.

[11] Some usages of the term suggest that the phenome of a given organism is best understood as a kind of matrix of data representing physical manifestation of phenotype.

For example, discussions led by A. Varki among those who had used the term up to 2003 suggested the following definition: "The body of information describing an organism's phenotypes, under the influences of genetic and environmental factors".

[14] In 2009, a research team demonstrated the feasibility of identifying genotype–phenotype associations using electronic health records (EHRs) linked to DNA biobanks.

These base pairs have a higher thermal stability (melting point) than adenine-thymine, a property that might convey, among organisms living in high-temperature environments, a selective advantage on variants enriched in GC content.

[19] Other biologists broadly agree that the extended phenotype concept is relevant, but consider that its role is largely explanatory, rather than assisting in the design of experimental tests.

For instance, an albino phenotype may be caused by a mutation in the gene encoding tyrosinase which is a key enzyme in melanin formation.

[citation needed] Changes in the levels of gene expression can be influenced by a variety of factors, such as environmental conditions, genetic variations, and epigenetic modifications.

An experiment involving machine learning methods utilizing gene expressions measured from RNA sequencing found that they can contain enough signal to separate individuals in the context of phenotype prediction.

[24][25] Phenomics is an important field of study because it can be used to figure out which genomic variants affect phenotypes which then can be used to explain things like health, disease, and evolutionary fitness.

This experiment involved the progeny of mice treated with ENU, or N-ethyl-N-nitrosourea, which is a potent mutagen that causes point mutations.

The mice were phenotypically screened for alterations in the different behavioral domains in order to find the number of putative mutants (see table for details).

[34] The same amino acid change causes human familial blindness, showing how phenotyping in animals can inform medical diagnostics and possibly therapy.